The present disclosure relates generally to systems and methods for separating various materials. In particular, the present disclosure relates to harvesters and separating various crops, for example tree nuts, from twigs, dirt, dust, and other debris.
Some harvesters presently on the market use various screening/roller assemblies to separate debris from harvested crop product. Separation of the debris from the crop in or near the location of harvesting may decrease the weight of the harvested crop and thus the cost of transportation, decrease the cost of disposal of the debris because it may be left in or near the harvesting location, and decrease the likelihood of contamination of the harvested product with the debris during transport. These screening/roller assemblies may have a series of rotating spaced parallel shafts, each of which has a series of disks. The screening/roller assemblies permit debris to pass downward through spaces between disks, while the harvested crop product remains over the disks and advances out of the screening/roller assembly to a collector. U.S. Pat. No. 8,683,918 presents an example of a known harvester.
A problem with known harvesters, such as the one of U.S. Pat. No. 8,683,918, is jamming. Screening/roller assemblies having disks with teeth or open-ended slots along the edge of the disk may create non-uniform spacing between disks on adjacent parallel shafts during rotation. The non-uniform spacing can result in debris or crop product being caught and jamming up the disks causing stoppages. Even if the jamming may not cause the entire apparatus to stop completely, it may cause momentary stoppages. Such stoppages may cause substantial mechanical shock that eventually results in premature failure of various components of the screening/roller assembly.
Disks that do not have open-ended slots along the edge of the disk are known, for example as disclosed in U.S. Pat. No. 5,960,964. However, assemblies such as the one in U.S. Pat. No. 5,960,964 have large axial gaps between disks mounted along a common shaft. These axial gaps are much larger than the radial gaps between cooperating disks on adjacent parallel rotation shafts. Such assemblies are not suitable for separating crop product from debris. Some crop product and debris will fall through the large gaps while other crop product and debris will not fall through the smaller gaps between the disks. Thus, such assemblies cannot reliably sort crop product from debris.
Another problem with known harvesters is dust created by the harvester. Typically, harvesters utilize high-volume air generated by an on-board fan assembly to assist the screening/roller assemblies in separating crop product from debris. These fan assemblies generate large amounts of dust. The dust can result in air pollution, water pollution, soil loss, human and animal health problems, and hazardous reductions in visibility during operation of the harvester. Additionally, dust can adversely impact various plants and crop product. Dust generation from agricultural machinery is particularly problematic in arid areas or areas with dusty or sandy soil conditions. In an effort to reduce dust production, some jurisdictions impose various air pollution control measures on agricultural equipment.
Thus, a need exists a need for improved systems for reliably and effectively separating harvested crop product from debris without being prone to jamming or generating large amounts of dust.